Communication apparatus, communication method, and program

ABSTRACT

A desirable connection form in consideration of a radio wave state is caused to be formed among three or more communication apparatuses. Group list information indicating three or more communication apparatuses, including local equipment, that have been set as a group for performing wireless communication is referred to so as to grasp communication apparatuses that have been set as the group. Then, a value indicating a degree of stability of communication between respective communication apparatuses indicated in the group list information is obtained, and a new connection form to which a change is desirably performed is determined by using the value indicating the degree of stability of communication between the respective communication apparatuses. Then, processing is performed for changing a connection state of respective communication apparatuses included in the group to the new connection form.

TECHNICAL FIELD

The present technology relates to a communication apparatus, acommunication method, and a program, and in particular, to processingfor a connection form in communication among three or more multiplepieces of equipment.

BACKGROUND ART

A Bluetooth (registered trademark) wireless technology is peer to peer(P2P) communications, and enables communication between pieces ofequipment which have been paired in advance.

Furthermore, Bluetooth communication is performed in units of a piconet.A piconet can be configured by one piece of master equipment and sevenpieces of slave equipment at maximum simultaneously.

Patent Document 1 listed below describes that a state of communicationbetween a master and a slave is periodically monitored and the masterand the slave are changed as needed.

CITATION LIST Patent Document

Patent Document 1: Japanese Patent No. 4378888

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

Meanwhile, communication apparatuses that enable calls in a group of aplurality of persons who are located at a short distance are useful. IfBluetooth communication apparatuses attached to helmets to be used formotorcycles, skiing, or the like are used, for example, calls can beenabled among companions located close to each other.

In this case, it is sufficient that a plurality of companions, such asthree or four companions, for example, pair their own communicationapparatus with respective communication apparatuses of the othercompanions so as to form a group.

In communication among three or more pieces of equipment, as describedabove, in a situation where respective pieces of equipment (users of therespective pieces of equipment) can freely move, an apparentcommunicable distance is determined depending on a connection form ofthe respective pieces of equipment. Therefore, users are required touse, for example, microphone headsets for motorcycles that use aBluetooth communication scheme, in consideration of a connection form.

For example, a case is assumed where there are equipment A, equipment B,and equipment C, equipment B is a master, and a connection form isequipment A-equipment B-equipment C. In this case, a user located at thehead uses equipment A, a user located in the next position usesequipment B, and a user located at the end uses equipment C. Thisenables the users to use these pieces of equipment at a maximumcommunicable distance.

However, in a case where a user of equipment B and a user of equipment Aare replaced with each other and alignment is changed to equipmentB-equipment A-equipment C, a communication distance from the head to theend becomes a communication distance between equipment B and equipmentC, and the communication distance is halved.

Therefore, in order to maintain a maximum communication distance, it isrequired that the users line up while being conscious of a connectionform to use the pieces of equipment. Alternatively, in a case where theusers change in alignment, it is required that connection be temporarilydisconnected and reestablished according to the alignment of the users.However, in both cases, the users are required to have knowledge inwireless and perform a complicated operation, and usability issignificantly reduced.

Note that Patent Document 1 describes that a master and a slave arereplaced with each other in accordance with a communication state, butdoes not disclose a practical method for detecting a communication statebetween slaves. Therefore, there remains a problem in which the masterand the slave fail to be smoothly replaced with each other.

Accordingly, it is an object of the present technology to enable adesirable connection form among, for example, three or more pieces ofequipment to be smoothly and easily obtained regardless of a positionalrelationship among users.

Solutions to Problems

A communication apparatus according to the present technology includes:a connection form determination unit that refers to group listinformation indicating three or more communication apparatuses that havebeen set as a group for performing wireless communication, the three ormore communication apparatuses including local equipment, obtains avalue indicating a degree of stability of communication betweenrespective communication apparatuses indicated in the group listinformation, and determines a new connection form by using the valueindicating the degree of stability of communication between therespective communication apparatuses; and a connection form changeprocessing unit that performs processing for causing the new connectionform determined by the connection form determination unit to be formedamong respective communication apparatuses included in the group.

Assume, for example, that, in a situation where three communicationapparatuses are grouped and in communication, one of the threecommunication apparatuses is set as master equipment and two of thethree communication apparatuses are set as pieces of slave equipment toform a piconet. In this case, there is no guarantee that this connectionform will always be maintained optimal. Accordingly, the connection formdetermination unit determines, for example, whether or not a currentconnection form is optimal in a present situation. If the currentconnection form is not optimal, the connection form determination unitdetermines a new more suitable connection form. The connection formchange processing unit performs processing for changing the currentconnection form to a connection form that has been determined to be moresuitable. For example, processing is performed for changing the masterequipment to other master equipment.

In the above-described communication apparatus according to the presenttechnology, it is conceivable that the connection form determinationunit starts processing for determining a connection form on the basis ofa user's operation.

In response to the user's operation, the connection form determinationunit determines a desirable connection state, and the connection formchange processing unit performs processing for changing a connectionform.

In the above-described communication apparatus according to the presenttechnology, it is conceivable that the connection form determinationunit obtains a value of a received signal strength indicator betweenrespective communication apparatuses indicated in the group listinformation, as the value indicating the degree of stability ofcommunication between the respective communication apparatuses.

In other words, a value of a received signal strength indicator betweenrespective communication apparatuses is confirmed for round-robincombinations of the three or more respective communication apparatuses.

In the above-described communication apparatus according to the presenttechnology, it is conceivable that the connection form determinationunit requests information relating to the received signal strengthindicator from a communication apparatus selected according to the grouplist information, and receives, from a communication apparatus servingas a request destination, the information relating to the receivedsignal strength indicator between the communication apparatus serving asthe request destination and another communication apparatus.

In other words, a value of a received signal strength indicator betweenanother communication apparatus in the group and each of thecommunication apparatuses is requested from the other communicationapparatus.

In the above-described communication apparatus according to the presenttechnology, it is conceivable that in a case where a communicationapparatus that has not yet been connected is selected in accordance withthe group list information, the connection form determination unitperforms processing for connection of communication with the selectedcommunication apparatus.

In other words, connection is established when the value of the receivedsignal strength indicator is requested from another communicationapparatus that has not yet been connected in the group.

In the above-described communication apparatus according to the presenttechnology, it is conceivable that the connection form determinationunit determines communication apparatuses having a lowest degree ofstability of communication therebetween, from among communicationapparatuses that have been set as the group, and that the connectionform change processing unit performs processing for disconnectingcommunication between the communication apparatuses having the lowestdegree of stability of communication.

In order to realize a desirable connection form, from among combinationsof respective communication apparatuses in the group, communicationapparatuses having the lowest degree of stability of communicationtherebetween are disconnected.

In the above-described communication apparatus according to the presenttechnology, it is conceivable that the connection form change processingunit performs processing for setting master equipment and slaveequipment in such a way that communication is available among therespective communication apparatuses that have been set as the group ina state where the communication between the communication apparatuseshaving the lowest degree of stability of communication therebetween hasbeen disconnected.

In other words, a relationship between master equipment and slaveequipment is optimized in such a way that respective pieces of equipmentcan perform communication in a state where certain communicationapparatuses having a low quality of communication have beendisconnected.

It is conceivable that the above-described communication apparatusaccording to the present technology further includes a sound input unit,a sound output unit, and a codec unit that encodes and decodes a soundsignal, and call sound is communicated.

In other words, the above-described communication apparatus according tothe present technology is a communication apparatus to be used in callsof conversation sound or the like.

A communication method according to the present technology is acommunication method of a communication apparatus, the communicationmethod including: a connection form determination procedure forreferring to group list information indicating three or morecommunication apparatuses that have been set as a group for performingwireless communication, the three or more communication apparatusesincluding local equipment, obtaining a value indicating a degree ofstability of communication between respective communication apparatusesindicated in the group list information, and determining a newconnection form by using the value indicating the degree of stability ofcommunication between the respective communication apparatuses; and aconnection form change processing procedure for performing processingfor causing the new connection form determined in the connection formdetermination procedure to be formed among respective communicationapparatuses included in the group.

A program according to the present technology is a program for causingan arithmetic processor that controls a communication apparatus toexecute a process including steps that correspond to the connection formdetermination procedure and the connection form change processingprocedure that have been described above.

Effects of the Invention

The present technology provides an effect in which a current connectionform is easily and smoothly changed into a new connection form thatcauses a communication state to be more improved. In particular, byusing a group list, the determination of a new connection form and achange into the new connection form are smoothly realized. This enablesa user's usability to be significantly improved.

Note that the effect described here is not necessarily restrictive, andany of effects described in the present disclosure may be exhibited.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram of a communication apparatus according to anembodiment of the present technology.

FIG. 2 is an explanatory diagram of a functional configuration of acontroller of the communication apparatus according to the embodiment.

FIG. 3 is an explanatory diagram of communication among communicationapparatuses according to the embodiment.

FIG. 4 is an explanatory diagram of generation of a group list accordingto the embodiment.

FIG. 5 is an explanatory diagram of connection form optimizationaccording to the embodiment.

FIG. 6 is a flowchart of a connection form optimization operationaccording to the embodiment.

FIG. 7 is a flowchart of the connection form optimization operationaccording to the embodiment.

FIG. 8 is a flowchart of processing of a communication apparatusaccording to the embodiment.

FIG. 9 is a flowchart of connection form optimization processingaccording to the embodiment.

FIG. 10 is a flowchart of the connection form optimization processingaccording to the embodiment.

MODE FOR CARRYING OUT THE INVENTION

An embodiment is described below in the following order.

-   -   <1. Configuration of communication apparatus>    -   <2. Grouping and group list>    -   <3. Connection form optimization operation>    -   <4. Example of processing of communication apparatus>    -   <5. Summary and modified examples>

<1. Configuration of Communication Apparatus>

In the embodiment, a communication apparatus 1 serving as Bluetoothcommunication equipment is used as an example. This communicationapparatus 1 is assumed to be equipment that enables sound communication(calls) with another communication apparatus 1 that has been paired in astate where a user wears or possesses the communication apparatus 1.

FIG. 1A illustrates a configuration of a communication apparatus 1according to the embodiment.

The communication apparatus 1 includes a system-on-a-chip (SoC) 10, anantenna 11, a speaker 12, and a microphone 13.

The SoC 10 is a Bluetooth SoC that has been generated as a device thatperforms Bluetooth communication control.

FIG. 1B illustrates an internal configuration example of the SoC 10.Note that, although an example using an SoC is illustrated here, an SoCform is not restrictive. It is sufficient that the communicationapparatus 1 has a configuration for performing Bluetooth communicationcontrol, as illustrated in FIG. 1B.

The communication apparatus 1 includes a controller 21, a memory 22, awireless communication unit 23, an audio codec 24, an audio interface25, an input amplifier 26, and an output amplifier 27.

The controller 21 is configured by a micro control unit (MCU), a digitalsignal processor (DSP), or the like, and controls an entire operation ofthe communication apparatus 1.

In the case of the present embodiment, the controller 21 is assumed tohave respective functions of a communication controller 21 a, a listinformation processing unit 21 b, a pairing processing unit 21 c, aconnection form determination unit 21 d, and a connection form changeprocessing unit 21 e that are illustrated in FIG. 2 in accordance withan operation program.

The communication controller 21 a is illustrated as a function ofcontrolling an entire operation of sound communication with anothercommunication apparatus 1 via the wireless communication unit 23.

The list information processing unit 21 b is a function of generating orobtaining a group list indicating equipment that is capable of wirelesscommunication and that has been selected as equipment that can fallunder a group for performing communication. The group list is used toefficiently perform a grouping operation to perform pairing among threeor more communication apparatuses 1. This group list is informationobtained by listing local equipment and pieces of equipment that havebeen selected as connection target equipment for group calls, from amongpieces of equipment capable of communication that exist near the localequipment.

In performing grouping in which three or more communication apparatuses1 are paired with each other and a sound communicable group is formed,in a case where a certain communication apparatus 1 serves as masterequipment, the certain communication apparatus 1 performs processing forgenerating the group list by using a function of the list informationprocessing unit 21 b.

Furthermore, in the case of a communication apparatus 1 serving as slaveequipment, the communication apparatus 1 performs processing forreceiving and obtaining a group list transmitted by anothercommunication apparatus 1, by using the function of the list informationprocessing unit 21 b.

The pairing processing unit 21 c performs normal one-to-one equipmentpairing processing. Furthermore, the pairing processing unit 21 c alsoperforms processing for performing pairing between respectivecommunication apparatuses 1 in order to enable three or morecommunication apparatuses 1 to perform group calls. In this case, agroup list is referred to, and processing is performed for pairingbetween local equipment and respective communication apparatuses 1indicated in the group list. In other words, the pairing processing unit21 c performs processing for pairing with a plurality of othercommunication apparatuses 1 in such a way that respective communicationapparatuses 1 listed in the group list are paired in all of thecombinations.

The connection form determination unit 21 d refers to the group list,and performs processing for obtaining a value indicating a degree ofstability of communication with each of the communication apparatuses 1indicated in the group list, and processing for determining a newdesirable connection form by using the value indicating the degree ofstability of communication with each of the communication apparatuses 1.

The value indicating the degree of stability of communication is, forexample, a value of a received signal strength indicator (RSSI).

The connection form change processing unit 21 e is a function ofperforming processing that causes a new connection form determined bythe connection form determination unit 21 d to be formed betweenrespective communication apparatuses 1 included in a group. For example,a new connection form that realizes more stable communication thancurrent communication is caused to be formed. For this purpose, forexample, processing, such as control to disconnect between prescribedcommunication apparatuses 1 or setting of a master and a slave, isperformed.

The connection form determination unit 21 d and the connection formchange processing unit 21 e are functions of performing connection formoptimization described later.

The memory 22 of FIG. 1B comprehensively indicates a read only memory(ROM), a random access memory (RAM), a flash ROM, and the like.

In the ROM and the flash ROM in the memory 22, a program for realizingthe respective functions illustrated in FIG. 2, a constant required forvarious types of processing, and the like are stored.

The RAM in the memory 22 is used as an arithmetic area of various typesof processing such as communication control, pairing processing, thegeneration of the group list, or connection form optimizationprocessing, or is used for temporary data storage.

Information relating to pairing equipment or the group list is stored inthe RAM or the flash ROM.

The wireless communication unit 23 is illustrated as a unit thatperforms sound data communication according to a Bluetooth communicationscheme via the antenna 11 under the control of the controller 21.

The audio codec 24 performs encoding and decoding for sound datacommunication. In other words, sound data of transmitted sound that hasbeen obtained using the microphone 13 is encoded, and is supplied to thewireless communication unit 23. Furthermore, sound data received by thewireless communication unit 23 is decoded.

Transmitted sound of a user is collected by the microphone 13. An analogsound signal collected by the microphone 13 is supplied to the inputamplifier 26. In the input amplifier 26, automatic gain control (AGC)processing, limiter processing, filter processing, processing forconversion to a digital signal, (A/D conversion), equalizing, or thelike is performed, and digital data of the transmitted sound is suppliedto the audio interface 25, and is transferred to the audio codec 24.Then, encoding processing is performed, and data is transmitted from thewireless communication unit 23.

Sound data of received sound that has been received by the wirelesscommunication unit 23 and has been decoded by the audio codec 24 issupplied to the output amplifier 27 via the audio interface 25. In theoutput amplifier 27, a sound signal on which equalizing, processing forconversion to an analog signal (D/A conversion), level adjustment,amplification using a power amplifier, or the like has been performed issupplied to the speaker 12, and sound is caused to be output from thespeaker 12.

As a communication apparatus 1 having the configuration described above,three communication apparatuses 1A, 1B, and 1C are illustrated in FIG.3A.

These communication apparatuses 1A, 1B, and 1C are connected accordingto the Bluetooth wireless scheme, and this enables mutual conversationvia sound within a wirelessly reachable range even in a case where usersare located far from each other, and this further enables all of theusers to make conversation.

FIG. 3B illustrates a state where the communication apparatuses 1A, 1B,and 1C have the longest communicable distance. Note that a state isillustrated where the communication apparatus 1B illustrated as a doublecircle serves as master equipment, the communication apparatuses 1A and1C illustrated as a single circle serve as pieces of slave equipment,and a piconet is formed.

Areas RRA, RRB, and RRC are respectively ranges that radio waves reachfrom the communication apparatuses 1A, 1B, and 1C. The pieces of slaveequipment are aligned on a straight line in the area RRB with thecommunication apparatus 1B serving as master equipment as a center, andtherefore a communicable distance between the communication apparatuses1A and 1C becomes maximum.

However, a positional relationship among respective users who possessthe communication apparatuses 1A, 1B, and 1C changes, and therefore amaximum communicable distance, as described above, is not alwaysobtained.

<2. Grouping and Group List>

Here, grouping for performing group calls among the three communicationapparatuses 1A, 1B, and 1C is described.

In order to perform sound communication using a Bluetooth wirelesstechnology, the communication apparatuses 1A, 1B, and 1C need to bepaired with each other in advance.

For example, in order to enable the communication apparatuses 1A, 1B,and 1C to be easily paired with each other, as described above, it isconceivable that a group list is generated and pairing is automaticallyperformed using the group list.

FIG. 4A illustrates pieces of equipment capable of Bluetoothcommunication that exist in the vicinity with the communicationapparatus 1A as a center. Note that a circular range RRA is assumed tobe a range that an ID packet transmitted from the communicationapparatus 1A reaches.

Here, it is assumed that communication apparatuses 1E, 1F, and 1G aresimilar communication apparatuses 1, but exist in relatively remotepositions.

It is assumed that each of equipment X1 and equipment X2 is alsoequipment capable of Bluetooth communication but is not equipment forsound calls with a communication apparatus 1. For example, each of theequipment X1 and the equipment X2 is assumed to be equipment such as amusic player or game equipment. The equipment X1 and the equipment X2exist in positions where they can communicate with the communicationapparatus 1A.

Here, a situation is assumed where three persons who possess thecommunication apparatuses 1A, 1B, and 1C desire to perform wirelesscalls in a group.

It is assumed that the respective communication apparatuses 1E, 1F, and1G are communication apparatus 1 that are possessed by other persons whohave no relationship with each other.

In a case where grouping is now performed with the communicationapparatus 1A as a master, equipment capable of Bluetooth communicationis searched for, so that the communication apparatuses 1A, 1B, and 1Cand the pieces of equipment X1 and X2 are detected.

The communication apparatus 1A selects pieces of equipment to begrouped, from among the detected pieces of equipment capable ofcommunication.

In this case, the equipment X1 and the equipment X2 can be excluded fromconnection target equipment by confirming equipment type information ofeach of the detected pieces of equipment.

Furthermore, even in a case where the communication apparatus 1G hasbeen detected, the communication apparatus 1G has an excessively lowreceived signal strength indicator. In response to this, thecommunication apparatus 1G can be excluded from the connection targetequipment by reducing the selection priority of the communicationapparatus 1G. Furthermore, by setting the number of pieces of equipmentto be included in a group to 3, the communication apparatus 1G can alsobe excluded from the connection target equipment due to the limit of thenumber of pieces of equipment.

As described above, the communication apparatus 1A selects pieces ofequipment in a group, and generates a group list obtained by listingrespective pieces of equipment that will belong to the group.

An example of the group list is illustrated in FIG. 4B.

Local equipment (the communication apparatus 1A) is described in a firstrow.

The communication apparatus 1B and the communication apparatus 1C thathave been selected as equipment in the group are described in a secondrow and a row that follows. The respective communication apparatuses 1A,1B, and 1C are indicated by using a Bluetooth device address (BD_ADDR).

As described above, the group list is generated as a list that indicatesall pieces of equipment in a group at the time of grouping.

By using this group list, the respective pieces of equipment in thegroup can be paired with each other automatically and efficiently.

For example, the communication apparatus 1A performs pairing with thecommunication apparatus 1B in accordance with the group list, andtransmits the group list to the communication apparatus 1B. Thecommunication apparatus 1A performs pairing with the communicationapparatus 1C in accordance with the group list, and transmits the grouplist to the communication apparatus 1C.

By doing this, pairing can be performed between the communicationapparatuses 1A and 1B and between the communication apparatuses 1A and1C. Next, the communication apparatus 1A issues, to the communicationapparatus 1B, an instruction to perform pairing according to the grouplist. The communication apparatus 1B searches for equipment that has notyet been paired in the group list, and performs pairing with thecommunication apparatus 1C that falls under the equipment that has notyet been paired. By doing this, all of the pieces of equipment have beenpaired with each other in a round-robin manner.

Furthermore, the respective communication apparatuses 1A, 1B, and 1Center into a state of possessing the group list.

<3. Connection Form Optimization Operation>

Even after grouping is performed such that calls become available,satisfactory calls are not always available. This is because callquality changes depending on a positional relationship among respectiveusers and a call available distance also changes. That is, a connectionform of the communication apparatuses 1A, 1B, and 1C that has been setonce is not always an optimal connection form. Accordingly, in thepresent embodiment, connection form change processing is performed forcausing a desirable connection form to be formed according to asituation.

An overview is described with reference to FIG. 5. It is assumed thatthe communication apparatuses 1A, 1B, and 1C are paired with each otherso as to form a single group and each of the communication apparatuses1A, 1B, and 1C possesses a group list as illustrated in FIG. 4B.

In FIG. 5A, it is assumed that the three communication apparatuses 1A,1B, and 1C have been connected to each other so as to form a piconet,the communication apparatus 1C serves as master equipment, and thecommunication apparatuses 1A and 1B serve as pieces of slave equipment.A state is illustrated where the communication apparatuses 1A and 1Chave been connected and the communication apparatuses 1B and 1C havebeen connected.

However, in a case where it is assumed that the communicationapparatuses 1A, 1B, and 1C move in a direction away from each other,this positional relationship indicates a state where a more desirableconnection form is conceivable. In some cases, the communicationapparatuses 1B and 1C are too far away from each other, and noiseincreases in a call between the communication apparatus 1A or 1C and thecommunication apparatus 1B or the call is likely to be interrupted.

For example, in such a case, connection form optimization is assumed tobe performed. First, RSSI values between respective communicationapparatuses 1 are collected.

The communication apparatuses 1A and 1B serving as slaves are notconnected, and therefore the communication apparatuses 1A and 1B arefirst connected in order to obtain an RSSI value (FIG. 5B). Note thatconnection has already been established between the communicationapparatuses 1A and 1C and between the communication apparatuses 1B and1C, and therefore RSSI values can be detected.

Next, an RSSI value between respective communication apparatuses 1 isobtained (FIG. 5C). That is, each of an RSSI (AB) value serving as areceived signal strength indicator between the communication apparatuses1A and 1B, an RSSI (AC) value serving as a received signal strengthindicator between the communication apparatuses 1A and 1C, and an RSSI(BC) value serving as a received signal strength indicator between thecommunication apparatuses 1B and 1C is obtained.

Here, it is assumed that RSSI (AC)>RSSI (AB)>RSSI (BC) is established.That is, the RSSI (BC) value between the communication apparatuses 1Band 1C is the smallest.

Connection having a small RSSI value is connection in which call qualityor a call available distance has a small margin. Accordingly, connectionhaving a smallest RSSI value, namely, connection between thecommunication apparatuses 1B and 1C, is disconnected (FIG. 5D).

Then, roles are adjusted among the respective communication apparatuses1, and a piconet is formed (FIG. 5E). In this case, a new connectionform is formed in which the communication apparatus 1A serves as masterequipment and the communication apparatuses 1B and 1C serve as pieces ofslave equipment.

Note that, in order to realize the connection form optimizationoperation described above, the respective communication apparatuses 1A,1B, and 1C need to have been paired with all of the communicationapparatuses that form a network and to have been grouped. Therefore, therespective communication apparatuses 1A, 1B, and 1C are assumed tointernally store the group list illustrated in FIG. 4B.

A specific example of the connection form optimization operation isdescribed in FIGS. 6 and 7. In the respective drawings, it is assumedthat there are the communication apparatuses 1A, 1B, and 1C of FIG. 5,and the respective drawings illustrate a flow of control processing ofthe controller 21 in each of the communication apparatuses 1 (1A, 1B,and 1C). A positional relationship among the communication apparatuses1A, 1B, and 1C corresponds to FIG. 5.

FIGS. 6 and 7 described above are flowcharts using, as an example, acase where a user of the communication apparatus 1A serving as slaveequipment has performed an operation to start connection formoptimization.

Note that “A1”, “B1”, and “C1” in FIG. 6 respectively indicate that theprocessing moves on to the same reference signs in FIG. 7.

First, the user of the communication apparatus 1A performs an operationof connection form optimization in the communication apparatus 1A. Thecommunication apparatus 1A detects the user's operation in step S1001.

In step S1002, the communication apparatus 1A performs processing forextracting a communication apparatus 1 that has not yet been connectedto the local equipment from the group list. In the group list, thecommunication apparatus 1A, the communication apparatus 1B, and thecommunication apparatus 1C are described in this order, and thecommunication apparatus 1A has already been connected to thecommunication apparatus 1C, but has not yet been connected to thecommunication apparatus 1B.

Next, in step S1003, the communication apparatus 1A transmits aconnection request to the communication apparatus 1B, and makes anattempt to establish connection with the communication apparatus 1B.

In step S1103, the communication apparatus 1B receives the connectionrequest from the communication apparatus 1A.

Then, the communication apparatus 1A performs processing forestablishing connection with the communication apparatus 1B in S1004,and the communication apparatus 1B performs processing for establishingconnection with the communication apparatus 1A in step S1104.

In this case, only the communication apparatuses 1A and 1B have not yetbeen connected to each other in the group list. Therefore, by performingthe processing described above, all of the connections are establishedamong the respective communication apparatuses 1A, 1B, and 1C in thegroup.

Next, in order to obtain an RSSI value between respective communicationapparatuses 1, the communication apparatus 1A issues an RSSI request tothe communication apparatus 1B in accordance with the order in the grouplist in step S1005.

In step S1105, the communication apparatus 1B receives the RSSI requestfrom the communication apparatus 1A.

In step S1106, the communication apparatus 1B transmits, to thecommunication apparatus 1A, RSSI values (between 1A and 1B and between1B and 1C) and the number of pieces of connected equipment “2”.

In step S1006, the communication apparatus 1A receives the RSSI values(between 1A and 1B and between 1B and 1C) and the number of pieces ofconnected equipment “2” from the communication apparatus 1B. By doingthis, the communication apparatus 1A can obtain an RSSI value betweenthe communication apparatuses 1A and 1B and an RSSI value between thecommunication apparatuses 1B and 1C.

Furthermore, by transmitting, to the communication apparatus 1A, thenumber of pieces of connected equipment of the communication apparatus1B, the communication apparatus 1A can determine whether or notconnection has been established between the communication apparatus 1Band the communication apparatus 1C. In this example, the communicationapparatus 1B is connected to two pieces of equipment, the communicationapparatus 1A and the communication apparatus 1C, and therefore thenumber of pieces of equipment is “2”. Therefore, there are two RSSIvalues.

Next, in step S1007, the communication apparatus 1A transmits an RSSIrequest to the communication apparatus 1C that is next in order, inaccordance with the group list.

In step S1207, the communication apparatus 1C receives the RSSI requestfrom the communication apparatus 1A.

In step S1208, the communication apparatus 1C transmits, to thecommunication apparatus 1A, RSSI values (between 1B and 1C and between1C and 1A) and the number of pieces of connected equipment “2”.

In step S1008, the communication apparatus 1A receives the RSSI values(between 1B and 1C and between 1C and 1A) and the number of pieces ofconnected equipment “2” from the communication apparatus 1C. By doingthis, the communication apparatus 1A can obtain an RSSI value betweenthe communication apparatuses 1B and 1C and an RSSI value between thecommunication apparatuses 1C and 1A.

Furthermore, by transmitting, to the communication apparatus 1A, thenumber of pieces of connected equipment of the communication apparatus1C, the communication apparatus 1A can determine whether or notconnection has been established between the communication apparatus 1Cand the communication apparatus 1B. In this example, the communicationapparatus 1C is connected to two pieces of equipment, the communicationapparatus 1A and the communication apparatus 1B, and therefore thenumber of pieces of equipment is “2”. Therefore, there are two RSSIvalues.

By performing the processing so far, the communication apparatus 1A havecollected all of the RSSI values between respective pieces of equipment.Accordingly, in step S1009, connection having a smallest RSSI value ofthe collected RSSI values is determined. For example, it is determinedthat the RSSI value between the communication apparatuses 1B and 1C isthe smallest.

Then, in step S1010, the communication apparatus 1A transmits adisconnection instruction to disconnect between the communicationapparatuses 1B and 1C to the communication apparatus 1B having a higherorder, in accordance with the order in the group list.

In step S1110, the communication apparatus 1B receives the disconnectioninstruction to disconnect between the communication apparatuses 1B and1C from the communication apparatus 1A.

In step S1111, the communication apparatus 1B transmits a disconnectionrequest to the communication apparatus 1C.

In step S1211, the communication apparatus 1C receives the disconnectionrequest from the communication apparatus 1B.

Then, the communication apparatus 1B performs processing fordisconnecting from the communication apparatus 1C in S1112 of FIG. 7,and the communication apparatus 1C performs processing for disconnectingfrom with the communication apparatus 1B in step S1212.

After disconnection has been completed, in step S1113, the communicationapparatus 1B reports the completion of disconnection to thecommunication apparatus 1A, because the communication apparatus 1B hasperformed disconnection processing in response to a disconnectioninstruction from the communication apparatus 1A.

In step S1013, the communication apparatus 1A receives the completion ofdisconnection from the communication apparatus 1B so as to confirmdisconnection between the communication apparatuses 1B and 1C.

Note that in a case where the communication apparatus 1A is included inconnection between communication apparatuses 1 that is to bedisconnected, the communication apparatus 1A itself issues adisconnection request to a connection destination and performsdisconnection processing.

Next, processing is performed for forming a piconet for performingstable communication. At this point in time, the communication apparatus1A is connected to two pieces of equipment, the communication apparatus1B and the communication apparatus 1C, and therefore, the communicationapparatus 1A needs to be master equipment.

Accordingly, in step S1014, the communication apparatus 1A issues, tothe communication apparatus 1B, a request that the communicationapparatus 1A become a master (a role switch request).

In step S1114, the communication apparatus 1B receives a master requestfrom the communication apparatus 1A.

In step S1115, the communication apparatus 1B makes a request acceptanceresponse to the communication apparatus 1A.

In step S1015, the communication apparatus 1A receives requestacceptance from the communication apparatus 1B, so that thecommunication apparatus 1A becomes a master for the communicationapparatus 1B.

Similarly, in step S1016, the communication apparatus 1A issues, to thecommunication apparatus 1C, a request that the communication apparatus1A become a master (the role switch request).

In step S1216, the communication apparatus 1C receives a master requestfrom the communication apparatus 1A.

In step S1217, the communication apparatus 1C makes a request acceptanceresponse to the communication apparatus 1A.

In step S1017, the communication apparatus 1A receives requestacceptance from the communication apparatus 1C, so that thecommunication apparatus 1A also becomes a master for the communicationapparatus 1C. As a result of the above, a piconet can be formed, andconnection form optimization is terminated.

Note that in the example described above, in a case where connectionfails to be established between the communication apparatus 1A and thecommunication apparatus 1B, namely, between slaves, an RSSI value is setto -∞, and the processing is completed in a state where a connectionform is left as it is, because connection physically fails to beestablished.

By performing the connection form optimization operation describedabove, an optimal connection form in consideration of a radio wave statecan be formed in a state where, for example, three pieces of equipmentare connected.

Furthermore, the three communication apparatuses 1A, 1B, and 1C havebeen registered in a group list, and each of the communicationapparatuses 1A, 1B, and 1C has obtained the group list. Therefore, anattempt can be made to establish connection between respective pieces ofequipment in accordance with the group list.

Pieces of equipment that have not yet been connected to each other canbe determined in accordance with the group list, and connection can beestablished.

Then, a received signal strength indicator (an RSSI value) betweenrespective pieces of equipment can be obtained in a state whereconnection has been established.

A desirable connection form can be obtained by comparing the obtainedRSSI values with each other and forming a new connection form in such away that connections between pieces of equipment that have a larger RSSIvalue are used.

To this end, connection between pieces of equipment that has a smallerRSSI value is disconnected, master/slave control is performed onrespective pieces of equipment, and a piconet is formed.

Note that even in a case where all of the three pieces of equipment, thecommunication apparatuses 1A, 1B, and 1C, are in a not-yet-connectedstate, an optimal connection form can be formed by establishingconnection between respective pieces of equipment in accordance with agroup list and performing the connection form optimization operation.

Furthermore, even in a case where two of the three pieces of equipment,the communication apparatuses 1A, 1B, and 1C, are connected and theother one is in the not-yet-connected state, an optimal connection formcan be formed by establishing connection between respective pieces ofequipment in accordance with the group list and performing theconnection form optimization operation.

<4. Example of Processing of Communication Apparatus>

A processing algorithm serving as a communication apparatus 1 thatenables the connection form optimization operation described above,namely, a processing algorithm principally serving as the connectionform determination unit 21 d and the connection form change processingunit 21 e, is described. An example of processing that is performed onthe basis of a program in the controller 21 is described below. Byperforming the processing described below, respective communicationapparatuses 1 can perform processing as the communication apparatuses1A, 1B, and 1C of FIGS. 6 and 7. Note that it is assumed that groupingis performed on three pieces of equipment, the communication apparatuses1A, 1B, and 1C serving as the communication apparatuses 1, as describedabove.

FIG. 8 illustrates loop processing of the controller 21 during a normaloperation. The controller 21 repeats a loop of monitoring and detectionof steps S101 to S109.

In step S101, the controller 21 monitors whether or not an operation toinstruct connection form optimization has been performed by a user. In acase where the operation is detected, the controller 21 performsconnection form optimization processing in step S110. Processing for theoperation described above of the communication apparatus 1A isperformed. This connection form optimization processing will bedescribed later with reference to FIGS. 9 and 10.

In step S102 of FIG. 8, the controller 21 determines whether or not aconnection request has been received from another communicationapparatus 1. In a case where the connection request has been receivedfrom another communication apparatus 1, the processing of the controller21 moves on to step S120, and the controller 21 establishes connectionwith a communication apparatus 1 serving as a request source. Thiscorresponds to, for example, the processes of steps S1103 and S1104performed by the communication apparatus 1B in FIG. 6.

In step S103 of FIG. 8, the controller 21 determines whether or not anRSSI request has been received from another communication apparatus 1.In a case where the RSSI request has been received from anothercommunication apparatus 1, the processing of the controller 21 moves onto step S130, the controller 21 generates information relating to anRSSI value between the local equipment and connected equipment and thenumber of pieces of connected equipment, and performs processing fortransmitting the information to a communication apparatus 1 serving as arequest source. This corresponds to, for example, the processes of stepsS1105 and S1106 performed by the communication apparatus 1B and theprocesses of steps S1207 and S1208 performed by the communicationapparatus 1C in FIG. 6.

In step S104 of FIG. 8, the controller 21 confirms whether or not a ringconnection instruction has been received from another communicationapparatus 1. The ring connection instruction is an instruction to causerespective communication apparatuses 1, the communication apparatuses1A, 1B, and 1C, to be connected to each other.

The example described in FIGS. 6 and 7 indicates a case where thecommunication apparatus 1A has started the connection form optimizationprocessing, but the communication apparatus 1C starts the connectionform optimization processing in some cases. This is a case where a userof the communication apparatus 1C has performed an operation to instructconnection form optimization.

In the case of the example described in FIGS. 6 and 7, the communicationapparatus 1A is not connected to the communication apparatus 1B in apiconet before the start of the connection form optimization processing.In this case, if the communication apparatus 1A itself issues aconnection request to the communication apparatus 1B, a ring connectionstate is obtained. However, in a case where the communication apparatus1C has started the connection form optimization processing, thecommunication apparatus 1C needs to cause either the communicationapparatus 1A or the communication apparatus 1B to establish connectionbetween the communication apparatuses 1A and 1B in order to obtain thering connection state. In such a case, the communication apparatus 1Ctransmits the ring connection instruction.

In a case where the controller 21 (for example, a controller 21 of ahigher-order apparatus in the group list from among the communicationapparatuses 1A and 1B) has received the ring connection instruction, thecontroller 21 transmits a ring connection request to a lower-ordercommunication apparatus 1 in the group list in step S140. Then, theestablishment of connection is confirmed in step S141, and a connectionestablishment report is transmitted to a communication apparatus servingas a transmission source of the ring connection instruction (forexample, the communication apparatus 1C) in step S142. At this time, anRSSI value between the local equipment and a communication apparatus 1with which connection has been established and the number of pieces ofconnected equipment are simultaneously transmitted.

In step S105 of FIG. 8, the controller 21 confirms whether or not a ringconnection request has been received from another communicationapparatus 1. In response to the receipt of the ring connection request,the controller 21 establishes connection with a communication apparatus1 serving as a request source in step S150.

In step S106, the controller 21 confirms whether or not a disconnectionrequest has been received from another communication apparatus 1. Inresponse to the receipt of the disconnection request, the controller 21causes disconnection from a communication apparatus 1 serving as arequest source in step S160. This corresponds to, for example, theprocesses of steps S1211 and S1212 performed by the communicationapparatus 1C in FIGS. 6 and 7.

In step S107 of FIG. 8, the controller 21 confirms whether or not adisconnection instruction has been received from another communicationapparatus 1. The disconnection instruction is an instruction issued by acommunication apparatus 1 serving as an instruction source to disconnectfrom another communication apparatus 1. An example is a disconnectioninstruction that the communication apparatus 1A transmits to thecommunication apparatus 1B in step S1010 of FIG. 6. Accordingly, thisstep S107 is an example of detection performed, for example, by thecontroller 21 of the communication apparatus 1B.

In response to the receipt of the disconnection instruction, thecontroller 21 transmits a disconnection request to a lower-ordercontroller apparatus 1 in the group list in step S170. Then,disconnection processing is performed in step S171, and in response tothe completion of disconnection, the controller 21 transmits adisconnection completion report to a communication apparatus 1 servingas a disconnection instruction source in step S172.

In step S108 of FIG. 8, the controller 21 confirms whether or not a roleswitch request, namely, a request for the exchange of master/slaveroles, has been received from another communication apparatus 1.

In a case where the role switch request has been received, thecontroller 21 makes the “accepted” response (request acceptance) in stepS180. This corresponds to, for example, the processes of steps S1114 andS1115 performed by the communication apparatus 1B and the processes ofsteps S1216 and S1217 performed by the communication apparatus 1C inFIG. 7.

In step S109 of FIG. 8, the controller 21 confirms whether or not masterapproval has been received from another communication apparatus 1. Forexample, the example of FIGS. 6 and 7 indicates a case where thecommunication apparatus 1A becomes master equipment after connectionform optimization, but the communication apparatus 1A determines thatthe communication apparatus 1B or the communication apparatus 1C is tobe master equipment, in some cases. In these cases, the communicationapparatus 1A transmits the master approval to the communicationapparatus 1B or 1C. In this case, in step S109, the controller 21 of thecontroller apparatus 1B or 1C confirms whether or not the masterapproval has been received.

In a case where the master approval has been received, the controller 21confirms whether or not connection to two pieces of equipment has beenestablished in step S190. Connection between communication apparatuses 1that has a smallest RSSI value has already been disconnected (see S1010of FIG. 6), and therefore a communication apparatus 1 that will becomemaster equipment is connected to two pieces of equipment. Accordingly,in a case where connection to two pieces of equipment has not beenestablished, no particular response is made to the master approval. In acase where connection to two pieces of equipment has been established,the controller 21 determines whether or not the local equipment ismaster equipment of a piconet in a present situation in step S191. Ifthe local equipment is master equipment in the present situation, noparticular response is needed. If the local equipment is not masterequipment, the controller 21 transmits the role switch request toanother communication apparatus 1 in such a way that the local equipmentbecomes master equipment in step S192.

The communication apparatuses 1 (1A, 1B, and 1C) perform the processingof FIG. 8 described above.

Then, a communication apparatus 1 that has started the connection formoptimization processing performs processing illustrated in FIGS. 9 and10 in step S110. Note that FIGS. 9 and 10 are illustrated as continuousprocessing.

As the connection form optimization processing of FIGS. 9 and 10, thecontroller 21 repeats the check loop processing of steps S201, S202,S203, S204, S205, and S206.

In step S201 of FIG. 9, the controller 21 confirms whether or not thecontroller 21 is in a connection form optimization state. If thecontroller 21 is in the connection form optimization state, theprocessing moves from step S201 to step S210. The controller 21 that hastransited to the connection form optimization state in step S110 inresponse to an operation detected in step S101 of FIG. 8, as describedabove, corresponds to this. In step S210, the controller 21 confirmswhether or not there is a communication apparatus 1 that has not yetbeen connected to the local equipment. In a case where there is acommunication apparatus 1 that has not yet been connected, thecontroller 21 transits to a connection processing state in step S212.

If there are no communication apparatuses 1 that have not yet beenconnected, the controller 21 transits to a state of obtaining an RSSIand the number of pieces of connected equipment in step S211.

In step S202, the controller 21 confirms whether or not the controller21 is in the connection processing state. The controller 21 that hasentered into the connection processing state in step S212 describedabove moves from step S202 to step S220, and issues a connection requestto a not-yet-connected communication apparatus 1 from amongcommunication apparatuses 1 indicated in the group list.

In response to the connection request, in step S221, connection isestablished in some cases, and connection fails to be established inother cases. For example, in a case where a distance to a communicationapparatus 1 serving as a connection request destination has increased,connection fails to be established. Therefore, in response to theconnection request, connection to respective other communicationapparatuses 1 can be established in some cases, connection to only someof the respective other communication apparatuses 1 can be establishedin some cases, and no connection to the respective other communicationapparatuses 1 can be established in some cases. The processing transitsto the next phase in accordance with a success/failure in connection.

In step S222, the processing of the controller 21 diverges in accordancewith whether or not connection to one or more communication apparatuses1 has been established.

In a case where no communication apparatuses 1 are not connected, thecontroller 21 transits to a standby state in step S223, and terminatesthe processing of FIGS. 9 and 10 (returns to FIG. 8).

In a case where one or more communication apparatuses 1 are connected,the controller 21 transits to the state of obtaining an RSSI and thenumber of pieces of connected equipment in step S224.

In step S203, the controller 21 confirms whether or not the controller21 is in the state of obtaining an RSSI and the number of pieces ofconnected equipment. In a case where the controller 21 has entered intothe state of obtaining an RSSI and the number of pieces of connectedequipment in step S211 or S224, the controller 21 moves from step S203to step S230.

In step S230, the controller 21 transmits an RSSI request to acommunication apparatus 1 under connection. In response to this, acommunication apparatus 1 serving as a request destination transmitsinformation relating to an RSSI value and the number of pieces ofconnected equipment in steps S103 and S130 of FIG. 8.

Accordingly, in step S231, the controller 21 receives the informationrelating to the RSSI value and the number of pieces of connectedequipment that has been transmitted from the communication apparatus 1serving as the request destination in response to the RSSI request.

In step S232, the controller 21 determines whether or not the localequipment is connected to two communication apparatuses 1.

In a case where the local equipment is not connected to twocommunication apparatuses 1, the controller 21 determines whether or nottwo other communication apparatuses 1 are connected to each other instep S233.

If two other communication apparatuses 1 are not connected to eachother, the controller 21 transits to a ring connection processing statein step S234.

If two other communication apparatuses 1 are connected to each other,the controller 21 transits to a role optimization processing state instep S235.

In a case where the local equipment is connected to two communicationapparatuses 1, the controller 21 determines whether or not two othercommunication apparatuses 1 are connected to each other in step S236.

If two other communication apparatuses 1 are not connected to eachother, the controller 21 transits to the ring connection processingstate in step S237.

If two other communication apparatuses 1 are connected to each other,the controller 21 transits to a disconnection processing state in stepS238.

In step S204 of FIG. 10, the controller 21 confirms whether or not thecontroller 21 is in the ring connection processing state. In a casewhere the controller 21 has entered into the ring connection processingstate in step S234 or S237 described above, the controller 21 moves fromstep S204 to step S240.

In step S240, the controller 21 transmits an instruction to establishconnection with yet another communication apparatus 1, namely, a ringconnection instruction, to a communication apparatus 1 under connectionthat has a higher order in the group list. This is the issuance of aninstruction to establish connection with another communication apparatus1 to a communication apparatus 1 on a higher-order side in the grouplist because two other communication apparatuses 1 are not connected toeach other from the viewpoint of a communication apparatus 1 that hasentered into the ring connection processing state.

In step S241, the controller 21 receives a report about the completionof connection that has been transmitted from a communication apparatus 1serving as an instruction destination in response to the ring connectioninstruction. At this time, an RSSI value between the communicationapparatus 1 serving as the instruction destination and yet anothercommunication apparatus 1 and the number of pieces of connectedequipment are also transmitted from the communication apparatus 1serving as the instruction destination, and therefore the RSSI value andthe number of pieces of connected equipment are obtained. This isbecause the communication apparatus 1 serving as the instructiondestination performs the processes of steps S140, S141, and S142 of FIG.8.

In step S242, the controller 21 transits to the disconnection processingstate.

In step S205, the controller 21 confirms whether or not the controller21 is in the disconnection processing state. In a case where thecontroller 21 has entered into the disconnection processing state instep S242 described above, the controller 21 moves from step S205 tostep S250.

In step S250, the controller 21 extracts connection having a smallestRSSI value in accordance with RSSI values between respectivecommunication apparatuses 1 and the numbers of pieces of connectedequipment of the respective communication apparatuses that have beenobtained so far.

In step S251, the processing diverges in accordance with whether or notthe extracted connection having the smallest RSSI value is connectionbetween the local equipment and another communication apparatus 1.

In a case where the extracted connection is connection between the localequipment and another communication apparatus 1, the controller 21 moveson to step S255, and transmits a disconnection request to acommunication apparatus 1 serving as a connection destination.

Then, the controller 21 performs disconnection processing in step S256.A communication apparatus 1 serving as a transmission destination of thedisconnection request performs disconnection processing in step S160 ofFIG. 8. Accordingly, communication is disconnected.

In step S257, the controller 21 transits to a role optimization state.

In a case where the extracted connection having the smallest RSSI valueis connection between other communication apparatuses 1 in the viewpointof the local equipment, the controller 21 moves on to step S252, andtransmits a disconnection instruction to another communication apparatus1. At this time, the controller 21 transmits the disconnectioninstruction to a communication apparatus 1 having a higher order in thegroup list from among two communication apparatuses 1 to bedisconnected.

In response to this, a communication apparatus 1 serving as atransmission destination performs the processes of steps S107, S170,S171, and S172 of FIG. 8. Accordingly, a disconnection completion reportis transmitted from the transmission destination.

The controller 21 confirms the completion of disconnection by receivingthe disconnection completion report from a communication apparatus 1serving as an instruction destination in step S253, and transits to therole optimization state in step S254.

In step S206, the controller 21 confirms whether or not the controller21 is in the role optimization state. In a case where the controller 21has entered into the role optimization state in step S254 or S257described above, the controller 21 moves from step S206 to step S260.

In step S260, the controller 21 confirms whether or not the localequipment is connected to two communication apparatuses 1. A connectionstate changes depending on which connection between communicationapparatuses 1 has been disconnected in the disconnection processingdescribed above, and the local equipment is either connected to twocommunication apparatuses 1 or is connected to only one communicationapparatus 1.

A case where the local equipment is connected to two communicationapparatuses 1 is a case where the local equipment will become masterequipment. Accordingly, the controller 21 moves on to step S264, andconfirms whether or not the local equipment is master equipment for eachof communication apparatuses 1 in a present situation. If the localequipment is master equipment for respective other communicationapparatuses 1, an optimal piconet has already been formed, and thereforethe connection form optimization processing is terminated with nochange, and the processing returns to the loop processing of FIG. 8.

If the local equipment is not master equipment for the respective othercommunication apparatuses 1, the controller 21 moves from step S264 tostep S265, and transmits a master request (a roll switch request) toanother communication apparatus 1 in such a way that the local equipmentwill become a master. In response to this, a communication apparatus 1serving as a request destination performs the processes of steps S108and S180 of FIG. 8, and transmits a request acceptance response.

In step S266, the controller 21 receives an acceptance response to themaster (role switch) request, and the local equipment becomes masterequipment. As a result of the above, the local equipment becomes masterequipment, and an optimal piconet is formed. Therefore, the connectionform optimization processing is terminated, and the processing returnsto the loop processing of FIG. 8.

In a case where it is determined in step S260 that the local equipmentis not connected to two communication apparatuses 1, the controller 21moves on to step S261, and transmits master approval to anothercommunication apparatus 1 that is connected to the local equipment. Thecommunication apparatus 1 to which the master approval has beentransmitted performs the processes of steps S109 to S192 of FIG. 8.

Specifically, from among communication apparatuses 1 to which the masterapproval has been transmitted, a communication apparatus 1 that isconnected to only one piece of equipment transmits does not perform anyparticular communication because a determination result in step S190 isNO. In contrast, a communication apparatus 1 that is connected to twopieces of equipment moves on to steps S190 and S191, and transmits amaster request in step S192 if the communication apparatus 1 is notmaster equipment.

Therefore, the controller 21 receives the master request in step S262.In step S263, the controller 21 transmits an acceptance response to acommunication apparatus 1 serving as a transmission source in responseto the master request. As a result of this, the communication apparatus1 serving as the transmission source of the master request becomesmaster equipment, and an optimal piconet is formed. Therefore, theconnection form optimization processing is terminated, and theprocessing returns to the loop processing of FIG. 8.

Respective communication apparatuses 1 are enabled to perform theprocessing of FIGS. 8, 9, and 10 described above, and therefore therespective communication apparatuses 1 perform a behavior of any of thecommunication apparatuses 1A, 1B, and 1C of FIGS. 6 and 7, and automaticconnection form optimization is performed.

<5. Summary and Modified Examples>

A communication apparatus 1 according to the embodiment described aboveincludes: a connection form determination unit 21 d that refers to agroup list indicating three or more communication apparatuses 1 thathave been set as a group for performing wireless communication, thethree or more communication apparatuses 1 including local equipment,obtains a value (an RSSI value) indicating a degree of stability ofcommunication between respective communication apparatuses 1 indicatedin the group list, and determines a new connection form by using thevalue indicating the degree of stability of communication between therespective communication apparatuses 1; and a connection form changeprocessing unit 21 e that performs processing for causing the newconnection form determined by the connection form determination unit 21d to be formed among respective communication apparatuses 1 included inthe group.

For example, in a state where three communication apparatuses aregrouped and in communication, in a case where one of the threecommunication apparatuses is set as master equipment and two of thethree communication apparatuses are set as pieces of slave equipment toform a piconet, there is no guarantee that this connection form willalways be maintained optimally. Accordingly, the connection formdetermination unit 21 d determines, for example, whether or not acurrent connection form is optimal in a present situation. If thecurrent connection form is not optimal, the connection formdetermination unit 21 d determines a new more suitable connection form.In other words, a determination is made in such a way that a piconet isre-formed while connection between communication apparatuses 1 having asmallest RSSI value is avoided (S240 to S242 and S250). The connectionform change processing unit 21 e performs processing for changing thecurrent connection form to a connection form that has been determined tobe more suitable. In other words, connection having a smallest RSSIvalue is disconnected, and role switching is performed as needed (S251to S257, S206, and S260 to S266).

When connection form optimization is started due to the functions of theconnection form determination unit 21 d and the connection form changeprocessing unit 21 e, it is determined whether or not a currentconnection form is suitable, and if the current connection form is notoptimal, the current connection form is changed to a new more suitableconnection form. That is, a change into a more suitable connection formis automatically performed adaptively to a present situation.Accordingly, a satisfactory communication state is easily realized.

In particular, by using a group list, as in the embodiment, smoothconnection form optimization is realized.

Even in a case where the group list is not used, for example, an RSSIbetween pieces of slave equipment that have not yet been connected canbe obtained in response to an inquiry. In other words, an RSSI betweenslaves can be obtained by making an inquiry so as to obtain a list ofdevices in the vicinity and determining communication apparatuses in agroup in the list, and a communication apparatus 1A that has startedconnection form optimization is caused to obtain the RSSI. However, thisprocessing normally requires a time period of several tens of seconds,and communication is not available during obtainment, and therefore thisprocessing is not suitable for practical use in many cases.

In the case of the present embodiment, addresses of respectivecommunication apparatuses in a group are known due to group listinformation. Therefore, an inquiry for searching for Bluetooth equipmentin the vicinity is not needed, and an RSSI between pieces of equipmentthat have not yet been connected can be obtained in a very short time.Therefore, connection form optimization can be completed withoutimposing any temporal stress on a user. Stated another way, a user doesnot need special consciousness.

Then, due to the connection form optimization described above, calls canbe restored to a satisfactory state (for example, a state with lessnoise), for example, in a case where call quality has deteriorated.Stated another way, calls in a group can be maintained in a satisfactorystate.

Users do not need to perform pairing or a connection operation accordingto a positional relationship among group members or the order of thegroup members.

Furthermore, even in a case where the respective users desire to changethe positional relationship among the group members or the order of thegroup members, a complicated operation such as pairing ordisconnection/reconnection processing is not required.

Furthermore, due to the connection form optimization function describedabove, the respective users can freely move without being conscious of aconnection form, and a stress imposed by calls can be relieved.

Furthermore, even in a case where a situation where radio waves areunavailable has occurred and, for example, one of three pieces ofequipment fails to establish connection, or other cases, a connectionform optimization function according to the embodiment enablesconnection between the two other pieces of equipment. This is because,for example, if master equipment moves physically far away, the threepieces of equipment enter into a not-yet-connected state, but aconnection state can easily change in such a way that the two otherpieces of equipment are connected to each other.

Furthermore, for example, in a situation where one of three pieces ofequipment is in the not-yet-connected state and the two other pieces areconnected to each other, in a case where the not-yet-connected one pieceof equipment has moved closer, connection form optimization can beperformed in such a way that connection is established. For example, acommunication apparatus 1 of a user who has moved closer startsconnection form optimization processing, so that a state can begenerated where calls are available among the three pieces of equipment.Alternatively, either of two communication apparatuses 1 connected toeach other starts the connection form optimization processing, so thatconnection among three pieces of equipment for which a connection formhas been optimized can be established. Calls are enabled while theconnection form is flexibly changed by performing the processing above,namely, in accordance with a positional state of the group members.

Thus, a communication apparatus 1 that is excellent in usability for auser to perform group calls can be provided.

In the embodiment, an example has been described where processing fordetermining a connection form is started on the basis of a user'soperation (see S1001 of FIG. 6 and S101 of FIG. 8). In other words, inresponse to the user's operation, the connection form determination unit21 d determines a desirable connection form, and the connection formchange processing unit 21 e performs processing for changing aconnection form.

By optimizing the connection form in response to the user's operation, acommunication apparatus 1 does not need to constantly check whether ornot connection form optimization is needed. This results in a reductionin a processing load on the communication apparatus 1.

Furthermore, an effect of reducing power consumption is exhibited by notconstantly performing processing for determining a connection state suchas the obtainment of an RSSI value, for example.

In use, it is sufficient if a user that is aware of a deterioration inthe quality of call sound, or the like performs an operation to issue aninstruction to start connection form optimization, and a burden ofperforming a troublesome operation is not imposed on the user. It issufficient if the user performs the operation described above when thereis much noise or it is difficult to hear sound, and normally, the userdoes not need to pay attention to a positional relationship or the like.

Note that in the embodiment, connection form optimization processing isstarted on the basis of a user's operation, but connection formoptimization can be automatically started.

For example, it is detected that a communication environment betweencommunication apparatuses 1 has significantly deteriorated, and in sucha case, the connection form optimization processing is automaticallystarted. Conceivable examples of a deterioration in a communicationenvironment include the monitoring of a packet error rate, or the like.For example, it is conceivable that, in a case where the communicationapparatus 1C has detected that an error rate of a communication packetfrom another communication apparatus 1B detected by the local equipmentexceeds a preset threshold, the communication apparatus 1C determinesthat connection form optimization is needed and the communicationapparatus 1C starts the connection form optimization processing.

In the embodiment, a value of a received signal strength indicator(RSSI) between respective communication apparatuses 1 indicated in agroup list is obtained as a value indicating a degree of stability ofcommunication between the respective communication apparatuses 1.

In other words, an RSSI value between respective communicationapparatuses 1 is confirmed for round-robin combinations of three or morerespective communication apparatuses 1.

By obtaining the RSSI value between respective communication apparatuses1, a communication state between respective communication apparatuses 1in a group can be determined. Then, a desirable connection form forperforming stable communication can be determined on the basis of therespective RSSI values.

Note that in a case where the RSSI value is obtained as processing fordetermining a connection form in response to a user's operation, asdescribed above, the RSSI value is monitored only when the connectionform is optimized, resulting in a reduction in power consumption.

Furthermore, the value indicating the degree of stability ofcommunication between respective communication apparatuses 1 is notlimited to the RSSI value. For example, other information, such as apacket error rate or a bit error rate that is detected betweenrespective communication apparatuses 1, may be employed.

In the embodiment, a case has been described where information relatingto a received signal strength indicator (an RSSI value) is requested ofa communication apparatus 1 selected according to the group list andinformation relating to a received signal strength indicator (an RSSIvalue) between a communication apparatus 1 serving as a requestdestination and another communication apparatus 1 is received from thecommunication apparatus 1 serving as the request destination (S230 andS231).

In other words, an RSSI value between another communication apparatus 1in the group and each of the communication apparatuses 1 is requestedfrom the other communication apparatus 1.

By doing this, an RSSI value between a communication apparatus 1 servingas a request destination and another communication apparatus 1 and anRSSI value between the communication apparatus 1 serving as the requestdestination and the local equipment can be obtained. By performing thisprocessing, the RSSI value can be confirmed for all of the combinationsof respective communication apparatuses 1 in the group.

In particular, by selecting a communication apparatus 1 serving as arequest destination in accordance with the group list, a communicationstate between respective communication apparatuses 1 in the group can beefficiently grasped.

In the embodiment, a case has been described where in a case where anot-yet-connected communication apparatus 1 has been selected inaccordance with the group list, processing for establishing connectionof communication with the selected communication apparatus 1 (S220 toS224). In other words, connection is established when the RSSI value isrequested from another communication apparatus 1 that has not yet beenconnected in the group.

By doing this, the RSSI value can also be obtained from anot-yet-connected communication apparatus 1 serving as a requestdestination. By using the group list, processing can be performed whilea not-yet-connected communication apparatus 1 is also grasped asequipment in the group.

In the embodiment, communication apparatuses 1 having a lowest degree ofstability of communication therebetween are determined from amongcommunication apparatuses 1 that have been set as a group, andprocessing is performed for disconnecting between the communicationapparatuses 1 having the lowest degree of stability of communicationtherebetween (S250 to S257).

In other words, in order to realize a desirable connection form, fromamong combinations of respective communication apparatuses 1 in thegroup, communication apparatuses 1 having the lowest degree of stabilityof communication are disconnected. By doing this, a desirable connectionform can be realized in which connections between communicationapparatuses 1 having a relatively high degree of stability ofcommunication are maintained.

In the embodiment, processing for setting master equipment and slaveequipment is performed in such a way that communication is availableamong respective communication apparatuses 1 that have been set as agroup in a state where communication has been disconnected betweencommunication apparatuses 1 having the lowest degree of stability ofcommunication therebetween (S260 to S266).

In other words, a relationship between master equipment and slaveequipment is optimized in such a way that respective pieces of equipmentcan perform communication in a state where certain communicationapparatuses 1 having a low quality of communication have beendisconnected.

This causes a desirable connection form to be reconstructed. In otherwords, as a result of optimizing the connection form, a piconet isformed, and stable communication can be performed.

The communication apparatus 1 according to the embodiment includes asound input unit (the microphone 13 and the input amplifier 26), a soundoutput unit (the speaker 12 and the output amplifier 27), and a codecunit (the audio codec 24) that encodes and decodes a sound signal, andcommunicates call sound.

As a communication apparatus for conversation communication or the like,a system that optimizes the connection form in accordance withsituations can be realized. In group calls, respective users areprovided with a call environment that is excellent in usability and thatdoes not impose, on the respective users, a stress such as a positionalrelationship among the respective users.

Note that a technology of the present disclosure is not limited to anexample of the embodiment.

Although the SoC 10 illustrated in FIG. 1 is configured, for example, bya Bluetooth wireless unit, an MCU, a DSP, a ROM, an I/O, a flash ROM, aRAM, an audio codec, an audio amplifier, and the like, respective unitscan be used in combination with each other as parts.

Furthermore, in the embodiment, an example has been described wherethree communication apparatuses 1 are used, but the present technologyis applicable to three or more communication apparatuses. In the case ofa communication apparatus 1 using Bluetooth communication, the presenttechnology can also be embodied by using three to eight communicationapparatuses 1.

Furthermore, the operation example illustrated in FIGS. 6 and 7 has beendescribed under the assumption of a case where the three communicationapparatuses 1A, 1B, and 1C have been connected. However, the presenttechnology can be performed even in a case where the three communicationapparatuses have not yet been connected or two of the threecommunication apparatuses have been connected.

Moreover, in a case where one of the three communication apparatuses hasentered into a not-yet-connected state because of a state where radiowaves do not physically reach the one, the present technology enablesconnection to be established between the two other communicationapparatuses. Next, in a case where the one not-yet-connectedcommunication apparatus has entered a range of distance that radio wavesreach, either the one not-yet-connected communication apparatus or thetwo communication apparatuses under connection can perform connectionaccording to the present technology, and three-apparatus connection inwhich a connection form has been optimized can be established.

Specific examples of a product to which the present technology isapplicable are assumed to be Bluetooth headsets, Bluetooth headphones,Bluetooth speakers, intercom equipment for motorcycles or bicycles, andthe like.

A program according to the embodiment is a program for causing aninformation processor an arithmetic processor (the controller 21) thatcontrols a communication apparatus 1 to execute: a connection formdetermination step of referring to a group list indicating three or morecommunication apparatuses 1 that have been set as a group for performingwireless communication, the three or more communication apparatuses 1including local equipment, obtaining a value indicating a degree ofstability of communication between respective communication apparatuses1 indicated in the group list, and determining a new connection form byusing the value indicating the degree of stability of communicationbetween the respective communication apparatuses 1; and a connectionform change processing step of performing processing for causing the newconnection form determined in the connection form determination step tobe formed among respective communication apparatuses 1 included in thegroup.

In other words, this is a program for causing the arithmetic processor(a computer apparatus) to perform the processing of FIGS. 8, 9, and 10.

The program described above enables the communication apparatus 1according to the present embodiment to be easily realized.

Then, the program described above can be stored, in advance, in arecording medium incorporated into equipment such as a computerapparatus, a ROM in a microcomputer including a CPU, or the like.Alternatively, the program described above can be temporarily orpermanently stored in a removable recording medium such as asemiconductor memory, a memory card, an optical disk, a magneto-opticaldisk, or a magnetic disk. Furthermore, such a removable recording mediumcan be provided as what is called package software.

Furthermore, the program described above can be installed in a personalcomputer or the like from the removable recording medium, or can bedownloaded from a download site via a network such as a LAN or theInternet.

Note that the effects described herein are only illustrative and are notrestrictive, and other effects may be exhibited.

Note that the present technology can also employ the configurationdescribed below.

(1) A communication apparatus including:

a connection form determination unit that refers to group listinformation indicating three or more communication apparatuses that havebeen set as a group for performing wireless communication, the three ormore communication apparatuses including local equipment, obtains avalue indicating a degree of stability of communication betweenrespective communication apparatuses indicated in the group listinformation, and determines a new connection form by using the valueindicating the degree of stability of communication between therespective communication apparatuses; and

a connection form change processing unit that performs processing forcausing the new connection form determined by the connection formdetermination unit to be formed among respective communicationapparatuses included in the group.

(2) The communication apparatus described in (1) described above,

in which the connection form determination unit starts processing fordetermining a connection form on the basis of a user's operation.

(3) The communication apparatus described in (1) or (2) described above,

in which the connection form determination unit obtains a value of areceived signal strength indicator between respective communicationapparatuses indicated in the group list information, as the valueindicating the degree of stability of communication between therespective communication apparatuses.

(4) The communication apparatus described in (3) described above,

in which the connection form determination unit requests informationrelating to the received signal strength indicator from a communicationapparatus selected according to the group list information, andreceives, from a communication apparatus serving as a requestdestination, the information relating to the received signal strengthindicator between the communication apparatus serving as the requestdestination and another communication apparatus.

(5) The communication apparatus described in (4) described above,

in which in a case where a communication apparatus that has not yet beenconnected is selected in accordance with the group list information, theconnection form determination unit performs processing for connection ofcommunication with the selected communication apparatus.

(6) The communication apparatus described in any of (1) to (5) describedabove,

in which the connection form determination unit determines communicationapparatuses having a lowest degree of stability of communicationtherebetween, from among communication apparatuses that have been set asthe group, and

the connection form change processing unit performs processing fordisconnecting communication between the communication apparatuses havingthe lowest degree of stability of communication.

(7) The communication apparatus described in (6) described above,

in which the connection form change processing unit performs processingfor setting master equipment and slave equipment in such a way thatcommunication is available among the respective communicationapparatuses that have been set as the group in a state where thecommunication between the communication apparatuses having the lowestdegree of stability of communication therebetween has been disconnected.

(8) The communication apparatus described in any of (1) to (7) describedabove, further including:

a sound input unit; a sound output unit; and a codec unit that encodesand decodes a sound signal,

in which call sound is communicated.

(9) A communication method of a communication apparatus, thecommunication method including:

a connection form determination procedure for referring to group listinformation indicating three or more communication apparatuses that havebeen set as a group for performing wireless communication, the three ormore communication apparatuses including local equipment, obtaining avalue indicating a degree of stability of communication betweenrespective communication apparatuses indicated in the group listinformation, and determining a new connection form by using the valueindicating the degree of stability of communication between therespective communication apparatuses; and

a connection form change processing procedure for performing processingfor causing the new connection form determined in the connection formdetermination procedure to be formed among respective communicationapparatuses included in the group.

(10) A program for causing an arithmetic processor that controls acommunication apparatus to execute:

a connection form determination step of referring to group listinformation indicating three or more communication apparatuses that havebeen set as a group for performing wireless communication, the three ormore communication apparatuses including local equipment, obtaining avalue indicating a degree of stability of communication betweenrespective communication apparatuses indicated in the group listinformation, and determining a new connection form by using the valueindicating the degree of stability of communication between therespective communication apparatuses; and

a connection form change processing step of performing processing forcausing the new connection form determined in the connection formdetermination step to be formed among respective communicationapparatuses included in the group.

REFERENCE SIGNS LIST

1, 1A, 1B, 1C Communication apparatus

10 Bluetooth SoC

11 Antenna

12 Speaker

13 Microphone

21 Controller

21 a Communication controller

21 b List information processing unit

21 c Pairing processing unit

21 d Connection form determination unit

21 e Connection form change processing unit

22 Memory

23 Wireless communication unit

24 Audio codec

25 Audio interface

26 Input amplifier

27 Output amplifier

1. A communication apparatus comprising: a connection form determinationunit that refers to group list information indicating three or morecommunication apparatuses that have been set as a group for performingwireless communication, the three or more communication apparatusesincluding local equipment, obtains a value indicating a degree ofstability of communication between respective communication apparatusesindicated in the group list information, and determines a new connectionform by using the value indicating the degree of stability ofcommunication between the respective communication apparatuses; and aconnection form change processing unit that performs processing forcausing the new connection form determined by the connection formdetermination unit to be formed among respective communicationapparatuses included in the group.
 2. The communication apparatusaccording to claim 1, wherein the connection form determination unitstarts processing for determining a connection form on a basis of auser's operation.
 3. The communication apparatus according to claim 1,wherein the connection form determination unit obtains a value of areceived signal strength indicator between respective communicationapparatuses indicated in the group list information, as the valueindicating the degree of stability of communication between therespective communication apparatuses.
 4. The communication apparatusaccording to claim 3, wherein the connection form determination unitrequests information relating to the received signal strength indicatorfrom a communication apparatus selected according to the group listinformation, and receives, from a communication apparatus serving as arequest destination, the information relating to the received signalstrength indicator between the communication apparatus serving as therequest destination and another communication apparatus.
 5. Thecommunication apparatus according to claim 4, wherein in a case where acommunication apparatus that has not yet been connected is selected inaccordance with the group list information, the connection formdetermination unit performs processing for connection of communicationwith the selected communication apparatus.
 6. The communicationapparatus according to claim 1, wherein the connection formdetermination unit determines communication apparatuses having a lowestdegree of stability of communication therebetween, from amongcommunication apparatuses that have been set as the group, and theconnection form change processing unit performs processing fordisconnecting communication between the communication apparatuses havingthe lowest degree of stability of communication.
 7. The communicationapparatus according to claim 6, wherein the connection form changeprocessing unit performs processing for setting master equipment andslave equipment in such a way that communication is available among therespective communication apparatuses that have been set as the group ina state where the communication between the communication apparatuseshaving the lowest degree of stability of communication therebetween hasbeen disconnected.
 8. The communication apparatus according to claim 1,further comprising: a sound input unit; a sound output unit; and a codecunit that encodes and decodes a sound signal, wherein call sound iscommunicated.
 9. A communication method of a communication apparatus,the communication method comprising: a connection form determinationprocedure for referring to group list information indicating three ormore communication apparatuses that have been set as a group forperforming wireless communication, the three or more communicationapparatuses including local equipment, obtaining a value indicating adegree of stability of communication between respective communicationapparatuses indicated in the group list information, and determining anew connection form by using the value indicating the degree ofstability of communication between the respective communicationapparatuses; and a connection form change processing procedure forperforming processing for causing the new connection form determined inthe connection form determination procedure to be formed amongrespective communication apparatuses included in the group.
 10. Aprogram for causing an arithmetic processor that controls acommunication apparatus to execute: a connection form determination stepof referring to group list information indicating three or morecommunication apparatuses that have been set as a group for performingwireless communication, the three or more communication apparatusesincluding local equipment, obtaining a value indicating a degree ofstability of communication between respective communication apparatusesindicated in the group list information, and determining a newconnection form by using the value indicating the degree of stability ofcommunication between the respective communication apparatuses; and aconnection form change processing step of performing processing forcausing the new connection form determined in the connection formdetermination step to be formed among respective communicationapparatuses included in the group.